Recent developments in radio frequency licensing such as spectrum sharing have introduced new possibilities for Mobile Network Operators (MNOs). In particular, proposed spectrum sharing schemes such as Licensed Spectrum Access (LSA, proposed mainly for Europe in the 2.3-2.4 GHz bands) and Spectrum Access System (SAS, proposed mainly in the U.S. for the 3.55-3.7 bands) may open up access to previously restricted wireless frequency bands for mobile communications by allowing MNOs to share certain spectrum bands with “incumbent” users.
Both LSA and SAS propose to use a ‘tiered’ approach to manage spectrum access where the incumbents occupy the highest ‘tier’ and thus have the highest priority to utilize the shared spectrum. Accordingly, licensed users may need to ensure that a given shared band is not being utilized by an incumbent before accessing the band. While LSA as currently proposed only specifies a two-tiered system of incumbents of licensees, the SAS framework additionally proposes another tier of ‘priority’ users which may enjoy access priority over lower priority or ‘general’ users while still yielding access to incumbents. Accordingly, the general users (referred to as General Authorized Access (GAA) users) may only be permitted to access shared spectrum when neither incumbents nor priority users (referred to as Priority Access License (PAL) users) are actively using the shared spectrum. General users may therefore need to perform sensing operations in order to determine when use of shared SAS spectrum is permitted, i.e. when no incumbents or priority users are active on the shared spectrum.